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Re: [RDF+OWL] First version OWL 2 RL embedding

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Wed, 17 Dec 2008 18:18:33 +0000
Message-ID: <49494279.8060505@hplb.hpl.hp.com>
To: Jos de Bruijn <debruijn@inf.unibz.it>
CC: RIF WG <public-rif-wg@w3.org>

Jos de Bruijn wrote:
> http://www.w3.org/2005/rules/wiki/SWC#Embedding_Normalized_OWL_2_RL
> 
> I did not yet check it thoroughly, but I think the embedding is already
> close to a version that works.
> 
> The embedding does not use negative guards.  Rather, it axiomatizes the
> behavior through a number of constraints.  For example, to ensure that
> values that are not in the value space of a particular datatype do not
> end up in its class extension, we use formulas:
> 
> ("a"="b" :- tr(s^^u)[rdf:type -> u']) for every well-typed literal s^^u
> and datatype identifier u' in V such that L2V(D(u))(s) is not in the
> value space of u'.
> 
> This is analogous to the dt-not-type rule in Table 8 of the OWL 2 RL
> rules in [1].

Makes sense.

> This confirms my suspicion that RDF and OWL compatibility does not
> require negative guards.
> As far as I'm concerned we can get rid of them.

In a theoretical but not necessarily in a practical sense.

First it would require us to only provide the translation approach to 
OWL 2 RL implementation and we would be unable to publish a static RIF 
rule set. That might be acceptable but the last discussion on this came 
to the opposite conclusion.

Second, if I understand correctly the above approach requires NDT 
separate type checking rule for *each* literal in the ontology (where 
NDT is the number of datatypes supported). For realistic scales of 
ontology that sounds like an unrealistic number of rules.

Dave
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Received on Wednesday, 17 December 2008 18:19:26 GMT

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